[Bug 1910505] [NEW] atomic failure linking with --enable-sanitizers on 32-bit Linux hosts

[Philippe Mathieu-Daudé]

Public bug reported:

As of commit 50536341b47, using --enable-sanitizers on 32-bit Linux host:
- displays various warnings
- fails linking

Using Ubuntu 18.04 (release 20201211.1) and Clang10 on i386:

[139/675] Compiling C object softmmu.fa.p/softmmu_icount.c.o
In file included from ../softmmu/icount.c:31:
In file included from include/exec/exec-all.h:23:
In file included from ../target/mips/cpu.h:4:
In file included from ../target/mips/cpu-qom.h:23:
In file included from include/hw/core/cpu.h:23:
In file included from include/hw/qdev-core.h:5:
In file included from include/qemu/bitmap.h:16:
In file included from include/qemu/bitops.h:17:
include/qemu/atomic.h:463:12: warning: misaligned atomic operation may
incur significant performance penalty [-Watomic-alignment]
    return qatomic_read__nocheck(ptr);
           ^
include/qemu/atomic.h:129:5: note: expanded from macro
'qatomic_read__nocheck'
    __atomic_load_n(ptr, __ATOMIC_RELAXED)
    ^
include/qemu/atomic.h:473:5: warning: misaligned atomic operation may
incur significant performance penalty [-Watomic-alignment]
    qatomic_set__nocheck(ptr, val);
    ^
include/qemu/atomic.h:138:5: note: expanded from macro
'qatomic_set__nocheck'
    __atomic_store_n(ptr, i, __ATOMIC_RELAXED)
    ^
2 warnings generated.
[...]

[850/2216] Linking target tests/test-hbitmap
FAILED: tests/test-hbitmap
clang  -o tests/test-hbitmap tests/test-hbitmap.p/test-hbitmap.c.o
tests/test-hbitmap.p/iothread.c.o -Wl,--as-needed -Wl,--no-undefined
-pie -Wl,--whole-archive libblock.fa libcrypto.fa libauthz.fa libqom.fa
libio.fa -Wl,--no-whole-archive -Wl,--warn-common -fsanitize=undefined
-fsanitize=address -Wl,-z,relro -Wl,-z,now -m32 -ggdb
-fstack-protector-strong -Wl,--start-group libqemuutil.a
subprojects/libvhost-user/libvhost-user-glib.a
subprojects/libvhost-user/libvhost-user.a libblock.fa libcrypto.fa
libauthz.fa libqom.fa libio.fa @block.syms -lgio-2.0 -lgobject-2.0
-lglib-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0 -pthread -lutil -lgnutls
-lm -lgthread-2.0 -lglib-2.0 /usr/lib/i386-linux-gnu/libglib-2.0.so
-liscsi -lgthread-2.0 -lglib-2.0 -laio -lcurl
/usr/lib/i386-linux-gnu/libz.so -lrbd -lrados -lnettle -lgnutls
-Wl,--end-group
libblock.fa(block_io.c.o): In function `stat64_max':
include/qemu/stats64.h:58: undefined reference to `__atomic_load_8'
include/qemu/stats64.h:60: undefined reference to
`__atomic_compare_exchange_8'
libblock.fa(block_qapi.c.o): In function `stat64_get':
include/qemu/stats64.h:40: undefined reference to `__atomic_load_8'
libqemuutil.a(util_qsp.c.o): In function `qatomic_set_u64':
include/qemu/atomic.h:478: undefined reference to `__atomic_store_8'
libqemuutil.a(util_qsp.c.o): In function `qatomic_read_u64':
include/qemu/atomic.h:468: undefined reference to `__atomic_load_8'
clang: error: linker command failed with exit code 1 (use -v to see
invocation)

Issue previously reported on the list here:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg770128.html

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1910505

Title:
  atomic failure linking with --enable-sanitizers on 32-bit Linux hosts

Status in QEMU:
  New

Bug description:
  As of commit 50536341b47, using --enable-sanitizers on 32-bit Linux host:
  - displays various warnings
  - fails linking

  Using Ubuntu 18.04 (release 20201211.1) and Clang10 on i386:

  [139/675] Compiling C object softmmu.fa.p/softmmu_icount.c.o
  In file included from ../softmmu/icount.c:31:
  In file included from include/exec/exec-all.h:23:
  In file included from ../target/mips/cpu.h:4:
  In file included from ../target/mips/cpu-qom.h:23:
  In file included from include/hw/core/cpu.h:23:
  In file included from include/hw/qdev-core.h:5:
  In file included from include/qemu/bitmap.h:16:
  In file included from include/qemu/bitops.h:17:
  include/qemu/atomic.h:463:12: warning: misaligned atomic operation may
  incur significant performance penalty [-Watomic-alignment]
      return qatomic_read__nocheck(ptr);
             ^
  include/qemu/atomic.h:129:5: note: expanded from macro
  'qatomic_read__nocheck'
      __atomic_load_n(ptr, __ATOMIC_RELAXED)
      ^
  include/qemu/atomic.h:473:5: warning: misaligned atomic operation may
  incur significant performance penalty [-Watomic-alignment]
      qatomic_set__nocheck(ptr, val);
      ^
  include/qemu/atomic.h:138:5: note: expanded from macro
  'qatomic_set__nocheck'
      __atomic_store_n(ptr, i, __ATOMIC_RELAXED)
      ^
  2 warnings generated.
  [...]

  [850/2216] Linking target tests/test-hbitmap
  FAILED: tests/test-hbitmap
  clang  -o tests/test-hbitmap tests/test-hbitmap.p/test-hbitmap.c.o
  tests/test-hbitmap.p/iothread.c.o -Wl,--as-needed -Wl,--no-undefined
  -pie -Wl,--whole-archive libblock.fa libcrypto.fa libauthz.fa libqom.fa
  libio.fa -Wl,--no-whole-archive -Wl,--warn-common -fsanitize=undefined
  -fsanitize=address -Wl,-z,relro -Wl,-z,now -m32 -ggdb
  -fstack-protector-strong -Wl,--start-group libqemuutil.a
  subprojects/libvhost-user/libvhost-user-glib.a
  subprojects/libvhost-user/libvhost-user.a libblock.fa libcrypto.fa
  libauthz.fa libqom.fa libio.fa @block.syms -lgio-2.0 -lgobject-2.0
  -lglib-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0 -pthread -lutil -lgnutls
  -lm -lgthread-2.0 -lglib-2.0 /usr/lib/i386-linux-gnu/libglib-2.0.so
  -liscsi -lgthread-2.0 -lglib-2.0 -laio -lcurl
  /usr/lib/i386-linux-gnu/libz.so -lrbd -lrados -lnettle -lgnutls
  -Wl,--end-group
  libblock.fa(block_io.c.o): In function `stat64_max':
  include/qemu/stats64.h:58: undefined reference to `__atomic_load_8'
  include/qemu/stats64.h:60: undefined reference to
  `__atomic_compare_exchange_8'
  libblock.fa(block_qapi.c.o): In function `stat64_get':
  include/qemu/stats64.h:40: undefined reference to `__atomic_load_8'
  libqemuutil.a(util_qsp.c.o): In function `qatomic_set_u64':
  include/qemu/atomic.h:478: undefined reference to `__atomic_store_8'
  libqemuutil.a(util_qsp.c.o): In function `qatomic_read_u64':
  include/qemu/atomic.h:468: undefined reference to `__atomic_load_8'
  clang: error: linker command failed with exit code 1 (use -v to see
  invocation)

  Issue previously reported on the list here:
  https://www.mail-archive.com/qemu-devel@nongnu.org/msg770128.html

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